US 5,850,231 A · Electronic device having ferroelectric memory

Abstract

An electronic device maintains data utilizing a ferroelectric memory, not requiring a backup power source voltage. Data such as schedule data and telephone number data is stored in a ferroelectric RAM which switches between a dynamic mode and a nonvolatile mode. When a clock mode is designated by a "CLK" key, a memory control circuit causes the ferroelectric RAM to be switched to the nonvolatile mode to maintain the data stored therein. When a schedule mode or a telephone mode is designated by means of a "Sch" key or a "Tel" key, the ferroelectric RAM is switched to the nonvolatile mode to write/read data therein/therefrom. When it is detected that a battery voltage is lowered or the battery is removed from the electronic device, the ferroelectric RAM is switched to the nonvolatile mode to protect the stored data.

Claims9

Dependent claims

An information storing system comprising an external memory medium and an electronic device to which the external memory medium is connectable and which writes/reads data to/from the external memory medium;

the external memory medium including a ferroelectric memory having a memory mode switching characteristic for switching between:
a dynamic memory mode capable of writing/reading data, and
a nonvolatile memory mode capable of holding stored data without a power supply;
and
the electronic device including:
a lock switch for preventing the external memory medium from being removed from the electronic device, and
control means for executing a control of designating the ferroelectric memory to the dynamic memory mode when said external memory medium is locked by the lock switch and for designating the ferroelectric memory to the nonvolatile memory mode when the lock switch is unlocked.

4 more elements

An electronic device having a plurality of functions in each of which a corresponding application program is executed, comprising:

a ferroelectric memory having a characteristic of memory mode which is switchable between:
(i) a dynamic memory mode capable of writing/reading data, and
(ii) a nonvolatile memory mode capable of holding stored data without a power supply;
selection means for selecting one function from among the plurality of functions of the electronic device in response to an operation of a user;
determining means for determining whether switching the memory mode of the ferroelectric memory is necessary or not when the one function is selected by said selection means;
and
mode control means for switching the memory mode of the ferroelectric memory when said determining means determines that the memory mode should be switched.

4 more elements

Dependencies are inferred from the claim text.

Electronic device having ferroelectric memory

Life of this patent

Electronic device having ferroelectric memory

Life of this patent

Abstract

Claims9